Augmentation of Chains.
Flexible links are called tension elements; and fluid con-
nections, as between boiler and engine, or accumulator and
machine, are termed pressure elements, but the latter are always
connected to lower pairs. A pump is kinematically the same as a
ratchet, the valves being equivalent to pawls (see Fig. 450).
Augmentation of Chains is the multiplication of parts,
for convenience or the reduction of friction. Trains of gearing,
and anti-friction rollers (Fig. 451), are examples.
Summing up, mechanism may be divided into simple chains,
formed of rigid or flexible links, which are again united by higher
or lower pairs ; and all chains must be dosed, either by the chain
or by external force.*
LIST OF KINEMATIC CHAINS.
Lower ( *• Crank chains :
pairing, t 2, Screw chains :
High [3- Pulley chains :
4. Wheel chains:
5. Cam chains:
1 Sliding and turning and screw
Tension and pressure elements.
pairing. ^ 5. Ratchet chains: Intermittent motion.
A driving and working end are recognised in each of thesey
corresponding to P and W respectively, and the
Velocity Ratio of P and W in Kinematic Chains
will now be investigated graphically. Considering the instan-
Friction closure is one form of force closure.